Image reading apparatus and method for controlling image reading apparatus

ABSTRACT

The image reading apparatus including a reading unit configured read an image of a document according to a read request transmitted from an external device, includes a detection unit configured to detect a state of the document to be read by the reading unit, a reception unit configured to receive a request from the external device to obtain a state of the image reading apparatus, a power supply unit configured to, in a power saving state where power supply to the reading unit and the detection unit is stopped, supply power to the detection unit based on the reception of the request, and a transmission unit configured to transmit the state of the document to be read by the reading unit detected by the detection unit to which the power is supplied by the power supply unit, to the external device as a response to the request.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Continuation of U.S. application Ser. No.15/135195, filed Apr. 21, 2016, which claims the benefit of JapanesePatent Application No. 2015-088854, filed Apr. 24, 2015, which arehereby incorporated by reference herein in their entireties.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to an image reading apparatus which readsan image of a document according to a read request from an externaldevice.

Description of the Related Art

An image reading apparatus has been known which reads an image of adocument according to a read request from an external device, generatesimage data corresponding to the image, and transmits the image data tothe external device. A function by which the image reading apparatusreads an image of a document according to a read request from anexternal device will hereinafter be referred to as a pullscan function.

Conventionally, if the image reading apparatus executes a pullscanfunction, the user needs to manually set the image reading apparatus toa pullscan mode. It has been necessary that the user manually sets thepullscan mode each time the pullscan function is executed. Hence, animage reading apparatus that automatically enters a pullscan mode andcan read an image of a document according to a read request from anexternal apparatus has been discussed.

Recent image reading apparatuses typically enters a power saving stateto reduce power consumption during standby time. A conventional imagereading apparatus which is manually set to the pullscan mode does notenter the power saving state if the image reading apparatus is set tothe pullscan mode by the user. Thus, there has not been a need to takeaccount of receiving the read request from the external device in thepower saving state.

An image reading apparatus that automatically enters the pullscan modeaccording to a read request from an external device may receive a readrequest when in the power saving state. In such a case, the imagereading apparatus needs to automatically recover from the power savingstate. According to Japanese Patent Application Laid-Open No.2014-230070, if an image reading apparatus receives a read request in apower saving state from an external device, the image reading apparatusrecovers from the power saving state and becomes able to read adocument.

The image reading apparatus discussed in Japanese Patent ApplicationLaid-Open No. 2014-230070 recovers from the power saving state if a readrequest for an image of a document is received. Therefore, the externaldevice cannot figure out a state of the document to be read beforetransmitting the read request. The image reading apparatus discussed inJapanese Patent Application Laid-Open No. 2014-230070 can thus recoverfrom the power saving state and start a read operation according to theread request although there is no document placed on an automaticdocument conveyance apparatus (hereinafter, referred to as an automaticdocument feeder (ADF)) which conveys a plurality of sheets to a readingunit one by one.

SUMMARY OF THE INVENTION

The present invention is directed to providing an image readingapparatus which can supply power to a detection unit configured todetect a state of a document based on a state acquisition requestreceived from an external device.

According to an aspect of the present invention, an image readingapparatus including a reading unit configured to read an image of adocument, the image reading apparatus reading an image of a documentaccording to a read request transmitted from an external device,includes a detection unit configured to detect a state of the documentto be read by the reading unit, a reception unit configured to receive astate acquisition request from the external device, the stateacquisition request being intended to obtain a state of the imagereading apparatus, a power supply unit configured to, in a power savingstate where power supply to the reading unit and the detection unit isstopped, supply power to the detection unit based on the reception ofthe state acquisition request made by the reception unit, and atransmission unit configured to transmit the state of the document to beread by the reading unit, detected by the detection unit to which thepower is supplied by the power supply unit, to the external device as aresponse to the state acquisition request.

Further features of the present invention will become apparent from thefollowing description of embodiments with reference to the attacheddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an overall view of a system including a multifunctionperipheral (MFP).

FIG. 2 is a block diagram of the MFP.

FIG. 3 is a software block diagram of the MFP.

FIG. 4 is a block diagram of an information processing apparatus.

FIG. 5 is a diagram illustrating a screen of a scan application.

FIG. 6 is a sequence diagram when a pullscan function is executed.

FIG. 7 is a diagram illustrating state information about a scanner unit.

FIG. 8 is a diagram illustrating the MFP in a power saving state.

FIG. 9 is a diagram illustrating the MFP in a sensor recovery state.

FIG. 10 is a flowchart illustrating an operation of the informationprocessing apparatus.

FIG. 11 is a diagram illustrating a screen of the scan applicationduring execution of a scan.

FIG. 12 is a diagram illustrating a screen displaying image data of thescan application.

FIG. 13 is a diagram illustrating an error screen of the scanapplication.

FIG. 14 is a flowchart illustrating an operation of the MFP.

DESCRIPTION OF THE EMBODIMENTS

Embodiments of the present invention will be described below withreference to the drawings.

A first embodiment will be described below. FIG. 1 is an overall view ofa system.

The system of FIG. 1 includes a multifunction peripheral (MFP) 1, aninformation processing apparatus 2, and a wireless network router 3. TheMFP 1 (image reading apparatus) includes a print function, a scanfunction, and a facsimile function. The MFP 1 receives a read requesttransmitted from the information processing apparatus 2 via the wirelessnetwork router 3, and reads an image of a document according to the readrequest. The MFP 1 then transmits digital image data of the read imageto the information processing apparatus 2 via the wireless networkrouter 3.

The information processing apparatus (external device) 2 is communicablyconnected with the MFP 1 via the wireless network router 3. Theinformation processing apparatus 2 and the wireless network router 3 areconnected by a wireless local area network (LAN). The MFP 1 and thewireless network router 3 are connected by a wired LAN. The informationprocessing apparatus 2 and the wireless network router 3 may beconnected by a wired LAN. Alternatively, the MFP 1 and the wirelessnetwork router 3 may be connected by a wireless LAN. Further, theinformation processing apparatus 2 and the MFP 1 may be directlyconnected by a network cable.

FIG. 2 is a block diagram of the MFP 1.

As illustrated in FIG. 2, the MFP 1 includes a control unit 10, anoperation unit 20, a printer unit 30, a scanner unit 40, a facsimileunit 50, and a sensor unit 60.

The control unit 10 controls the operation unit 20, the printer unit 30,the scanner unit 40, and the facsimile unit 50 which are connected tothe control unit 10.

The operation unit 20 includes various buttons and a display unit to beoperated by a user. The display unit is a liquid crystal displayincluding a touch panel function, and accepts touch operations from theuser.

The printer unit 30 outputs a digital image to a sheet.

The scanner unit 40 optically reads an image from a document andgenerates digital image data.

The facsimile unit 50 is connected to a public switched telephonenetwork (PSTN) line. The facsimile unit transmits and receives facsimiledata to/from a not-illustrated facsimile apparatus.

The sensor unit 60 detects whether a document is placed on an ADF of thescanner unit 40.

Next, details of the control unit 10 will be described.

The control unit 10 includes a central processing unit (CPU) 11, arandom access memory (RAM) 12, a read-only memory (ROM) 13, and a harddisk drive (HDD) 14. The control unit 10 also includes a networkinterface (hereinafter, referred to as a network interface card (NIC))15, and an operation unit interface (operation unit I/F) 21. The controlunit 10 also includes a printer unit interface (hereinafter, referred toas a printer unit I/F) 31, and a scanner unit interface (hereinafter,referred to as a scanner unit I/F) 41. The control unit 10 also includesa facsimile unit interface (hereinafter, referred to as a facsimile unitI/F) 51. The control unit 10 also includes a sensor unit interface(hereinafter, referred to as a sensor unit I/F) 61.

The CPU 11 performs various types of data processing based on a programor programs. The CPU 11 controls the devices connected to a system bus16 in a centralized manner. The RAM 12 is a main storage unit for CPU 11operation. Examples of the RAM 12 include a dynamic random access memory(DRAM). The ROM 13 stores a boot program of the system. The HDD 14 is asecondary storage unit. The HDD 14 stores an operating system and aprint job received via the NIC 15.

The NIC 15 is an interface for communicating with an external device viaa LAN. The printer unit I/F 31 is an interface for communicating withthe printer unit 30. Data of an image to be printed by the printer unit30 is transmitted from the control unit 10 via the printer unit I/F 31.The scanner unit I/F 41 is an interface for communicating with thescanner unit 40. Image data (binary data) of an image read by thescanner unit 40 is transmitted to the control unit 10 via the scannerunit I/F 41. The operation unit I/F 21 is an interface for communicatingwith the operation unit 20.

The sensor unit I/F 61 is an interface for communicating with the sensorunit 60. If a document is placed on the ADF, the sensor unit I/F 61receives information indicating that a document is placed on the ADFfrom the sensor unit 60.

The scanner unit 40 includes an ADF 42 and a reading unit 43 which readsan image of a document.

FIG. 3 is a software block diagram of the MFP 1.

The units illustrated in solid lines in FIG. 3 are software modules thatare operated by the CPU 11 reading and executing a program or programsstored in the ROM 13 or the HDD 14.

A user interface (UI) module 301 provides various types of informationto the user via the operation unit 20, and accepts various instructionsfrom the user. A job controller 302 accepts jobs such as copy, print,and facsimile, and controls execution of the accepted jobs. A protocolstack 304 holds various network protocols such as the Transfer ControlProtocol/Internet Protocol (TCP/IP) and the Hypertext Transfer Protocol(HTTP).

In the present embodiment, data transmitted from the informationprocessing apparatus 2 is received via the network interface controller(NIC) 15 according to a network protocol held in the protocol stack 304.Received image data is stored by an image file 303. The image file 303is a software module that manages image data stored in the RAM 12 andthe HDD 14.

The image file 303 manages not only the image data received via the NIC15 but also image data generated by the scanner unit 40. The generationof the image data by the scanner unit 40 is controlled by a scan module306. A facsimile (FAX) module 305 controls facsimile communicationcarried out by the facsimile unit 50. When the MFP 1 performs facsimiletransmission, the FAX module 305 reads and transmits image data managedby the image file 303.

An operating system (OS) 308 adjusts modules and tasks, and manages theentire software of the MFP 1. The OS 308 controls device drivers 307.The device drivers 307 control hardware devices such as the scanner unit40 and the facsimile unit 50.

FIG. 4 is a block diagram of the information processing apparatus 2.

As illustrated in FIG. 4, the information processing apparatus 2includes a control unit 70 which controls the information processingapparatus 2, an operation unit 80 such as a keyboard and a mouse, and adisplay unit 90 which displays an image. The control unit includes a CPU71, a RAM 72, a ROM 73, an HDD 74, a network I/F 75, an operation unitI/F 81, and a display unit I/F 91.

In the present embodiment, a scan application for causing the MFP 1 toexecute a pullscan function is stored in the HDD 74.

The scan application, if executed by the CPU 71, displays the screen ofFIG. 5 on the display unit 90.

The screen of FIG. 5 includes a read image display area 500 fordisplaying an image read by the scanner unit 40. The screen includes acolor mode specification section 501 for specifying a color mode inwhich to read a document, a resolution specification section 502 forspecifying resolution in which to read the document, and an input methodspecification section 503 for specifying an input method of thedocument.

The user selects a monochrome mode or a color mode from a list in thecolor mode specification section 501. If the user selects the monochromemode, the scanner unit 40 generates digital monochrome image data. Ifthe user selects the color mode, the scanner unit 40 generates digitalcolor image data.

The user selects resolution in which the scanner unit 40 reads an image,from a list in the resolution specification section 502. The scannerunit 40 reads a document in the resolution specified by the user.

The user selects any one of auto, a pressing plate, and an ADF from alist in the input method specification section 503. If the user selectsthe pressing plate, the scanner unit 40 reads an image of a documentplaced on a glass plate. If the user selects the ADF, the scanner unit40 reads an image of a document placed on the ADF 42. If the userselects auto and a document is placed on the ADF 42, the scanner unit 40reads the document placed on the ADF 42. If no document is placed on theADF 42, the scanner unit 40 reads a document placed on the glass plate.

The MFP 1 does not include a unit that detects whether a document isplaced on the glass plate. Accordingly, if the user selects the pressingplate or if the user selects auto and no document is placed on the ADF42, the scanner unit 40 performs reading even when no document is placedon the glass plate.

The screen of FIG. 5 includes a read start button 504 for making thescanner unit 40 start reading a document.

<Pullscan Sequence>

FIG. 6 is a sequence diagram when the pullscan function is executed.

Initially, the user operates the operation unit of the informationprocessing apparatus 2 to give an instruction to execute the scanapplication. According to the instruction from the user, the CPU 71executes the scan application. As a result, the screen of FIG. 5 isdisplayed on the display unit 90.

The user then operates the operation unit 80 to select a color mode,resolution, and an input method on the screen of FIG. 5, and selects theread start button 504. In step S601, according to the selection of theread start button 504 by the user, the information processing apparatus2 transmits a request to obtain a state of the scanner unit 40(hereinafter, referred to as a state acquisition request) to the MFP 1.

If the NIC 15 receives the state acquisition request when the MFP 1 isin a power saving state (see FIG. 8), then in step S602, the NIC 15issues an interrupt to the CPU 11. In step S603, the CPU 11 receivingthe interrupt recovers from the power conserving state. In step S604,the CPU 11 having recovered from the power conserving state performscontrol such that power is supplied to the sensor unit 60. As a result,the MFP 1 enters a sensor recovery state illustrated in FIG. 9. In theforegoing power saving state, as illustrated in FIG. 8, power issupplied to the operation unit 20, the facsimile unit 50, the operationunit I/F 21, the NIC 15, and the facsimile unit I/F 51. Power supply tothe other portions is stopped. In the sensor recovery state, power issupplied to the operation unit 20, the facsimile unit 50, the operationunit I/F 21, the NIC 15, the facsimile unit I/F 51, the sensor unit 60,and the sensor unit I/F 61. The power supply to the other portions isstopped.

The CPU 11 obtains information indicating whether a document is placedon the ADF 42, from the sensor unit 60 to which the power is supplied.In steps S605 and S606, the CPU 11 transmits the information indicatingthe state of the scanner unit 40 (hereinafter, referred to as stateinformation) to the information processing apparatus 2 via the NIC 15.

Now, details of the information (state information) indicating the stateof the scanner unit 40 will be described.

FIG. 7 illustrates the information indicating the state of the scannerunit 40. The information (state information) indicating the state of thescanner unit 40 includes information 701 indicating an execution stateof the scanner unit 40, information 702 indicating whether a document isplaced on the ADF 42, and information 703 indicating an error. Examplesof the information 701 indicating the execution state of the scannerunit 40 include information indicating an idle state and informationindicating that the scanner unit 40 is in the process of scanning.Examples of the information indicating an error include informationindicating paper jam and information indicating the absence of an error.

In step S607, the CPU 11 having transmitted the information indicatingthe state of the scanner unit 40 to the information processing apparatus2 shifts the MFP 1 to the power saving state when the processingcorresponding to the state acquisition request ends.

In step S608, the CPU 71 of the information processing apparatus 2controls transmission of the read request based on the receivedinformation indicating the state of the scanner unit 40. Details of thetransmission control of the read request by the CPU 71 will be describedbelow.

If the NIC 15 receives the read request in the power saving state, thenin step S609, the NIC 15 issues an interrupt to the CPU 11. In stepS610, the CPU 11 having received the interrupt recovers from the powersaving state. In step S611, the CPU 11 performs control such that poweris supplied to the scanner unit 40. As a result, the MFP 1 enters astandby state illustrated in FIG. 2. In the standby state, power issupplied to each unit of the MFP 1. In the example described above, theMFP 1 enters the standby state if the read request is received. However,the power supply to the printer unit 30 and the printer unit I/F 31 mayremain stopped.

If the read request is received, then in steps S612 and S613, the CPU 11transmits a scan start acceptance response (hereinafter, referred to asan acceptance response) to the information processing apparatus 2. Instep S614, the CPU 11 instructs the scanner unit 40 to read an image ofa document in response to the reception of the read request. The scannerunit 40 having received the instruction starts to read an image of adocument.

In steps S615 and S616, to obtain image data of the image read by thescanner unit 40, the information processing apparatus 2 having receivedthe acceptance response transmits an acquisition request for the imagedata to the MFP 1. If the scanner unit 40 is in the process of scanning,then in steps S617 and S618, the CPU 11 having received the acquisitionrequest for the image data transmits status information indicating thatthe scanner unit 40 is in the process of scanning to the informationprocessing apparatus 2. If the scanner unit 40 is in the process ofscanning, then in steps S619 and S620, the information processingapparatus 2 transmits the acquisition request for the image data againafter a lapse of a predetermined time. If the reading of the document iscompleted, then in steps S621 and S622, the CPU 11 having received theacquisition request for the image data transmits the obtained image datato the information processing apparatus 2.

<Description of Operation of Information Processing Apparatus 2>

FIG. 10 is a flowchart illustrating an operation of the informationprocessing apparatus 2 when the scan application is executed.

Initially, the user operates the operation unit 20 to activate the scanapplication. In steps S1000, S1001, and S1002, the user having activatedthe scan application selects a color mode, resolution, and an inputmethod. In step S1003, the user presses the read start button 504. Ifthe read start button 405 is pressed, then in step S1004, the CPU 71 ofthe information processing apparatus 2 determines which input method isselected in step S1002.

If auto is selected as the input method (AUTO in step S1004), then instep S1005, the CPU 71 transmits a state acquisition request. In stepS1006, the CPU 71 determines whether a document is placed on the ADF 42,based on state information obtained as a response to the stateacquisition request. The following description will be given on theassumption that the executing state of the scanner unit 40 is an idlestate and the information about an error indicates the absence of anerror.

If the CPU 71 determines that no document is placed on the ADF 42 (NO instep S1006), then in step S1007, the CPU 71 transmits a read request(pressing plate) so that an image of a document placed on the glassplate is read. In step S1008, the CPU 71 determines whether anacceptance response is received from the MFP 1. If the CPU 71 determinesthat an acceptance response is received (YES in step S1008), then instep S1009, the CPU 71 transmits an acquisition request to obtain imagedata read by the scanner unit 40. If the scanner unit 40 is in theprocess of reading an image, the CPU 71 displays information indicatingthat a scan is in process on the display unit 90 as illustrated in FIG.11.

In step S1010, the CPU 71 obtains the image data from the MFP 1 as aresponse to the acquisition request. The obtained image data isdisplayed on the display unit 90 as illustrated in FIG. 12.

In step S1006, if the CPU 71 determines that a document is placed on theADF 42 (YES in step S1006), the processing proceeds to steps S1014 toS1017. The processing of steps S1014 to S1017 will be described below.

If the ADF 42 is selected as the input method (ADF in step S1004), thenin step S1011, the CPU 71 transmits a state acquisition request. In stepS1012, the CPU 71 determines whether a document is placed on the ADF 42,based on state information obtained as a response to the stateacquisition request.

If the CPU 71 determines that no document is placed on the ADF 42 (NO instep S1012), then in step S1013, the CPU 71 displays an error screen 105on the display unit 90 as illustrated in FIG. 13.

If the CPU 71 determines that a document is placed on the ADF 42 (YES instep S1012), then in step S1014, the CPU 71 transmits a read request(ADF 42) so that an image of the document placed on the ADF 42 is read.In step S1015, the CPU 71 determines whether an acceptance request isreceived from the MFP 1. If the CPU 71 determines that an acceptancerequest is received (YES in step S1015), then in step S1016, the CPU 71transmits an acquisition request for image data (hereinafter, referredto as an image data request) to obtain image data read by the scannerunit 40. In step S1017, the CPU 71 obtains the image data from the MFP 1as a response to the image data request.

If the pressing plate is selected as the input method (PRESSING PLATE instep S1004), then in step S1018, the CPU 71 transmits a stateacquisition request. The processing then proceeds to the foregoing stepsS1007 to S1010.

<Description of Operation of MFP 1>

FIG. 14 is a flowchart illustrating an operation of the MFP 1 whenrecovering from the power saving state.

When the MFP 1 is in the power saving state, the CPU 11 is in a powersaving state. In step S1401, if input of an interrupt into an interruptport of the CPU 11 in the power saving state is detected (YES in stepS1401), the CPU 11 recovers from the power conserving state. In stepS1402, the CPU 11 having recovered from the power conserving statedetermines whether the factor responsible for the interrupt is a stateacquisition request transmitted from the information processingapparatus 2. If the factor responsible for the interrupt is determinedto be the state acquisition request (YES in step S1402), then in stepS1403, the CPU 11 determines whether the state acquisition request is inaccordance with a pullscan protocol.

If the state acquisition request does not necessarily involve a readoperation of the scanner unit 40, the exact state of the scanner unit 40does not need to be obtained. For example, in the case of a remoteaccess function by which the MFP 1 can be accessed from a web browser ofthe information processing apparatus 2 to check the state of the MFP 1,the exact state of the scanner unit does not need to be displayed. Inthe present embodiment, the MFP 1 therefore does not recover from thepower saving state if the state acquisition request is not in accordancewith the pullscan protocol. This can prevent an increase in the powerconsumption due to the recovery from the power saving state. Inaddition, a driving noise originating out of the device(s) supplied withpower can also be prevented.

If the received state acquisition request is in accordance with thepullscan protocol (YES in step S1403), then in step S1404, the CPU 11makes the sensor unit 60 recover to obtain the exact state of thescanner unit 40. Specifically, the CPU 11 performs control such thatpower is supplied to the sensor unit I/F 61 and the sensor unit 60. Instep S1405, the CPU 11 obtains the state of the scanner unit 14 from thesensor unit 60, and updates the state of the sensor unit 40. In stepS1406, the CPU 11 transmits the information indicating the updated stateof the scanner unit 40, and then performs power saving processing toenter the power saving state.

Subsequently, if, when the MFP 1 is in the power saving state, input ofthe interrupt into the interrupt port of the CPU 11 is detected (YES instep S1407), the CPU 11 recovers from the power saving state. In stepS1408, the CPU 11 having recovered from the power saving statedetermines whether the factor responsible for the interrupt is a readrequest transmitted from the information processing apparatus 2. If thefactor responsible for the interrupt is determined to be the readrequest (YES in step S1408), then in step S1409, the CPU 11 makes theMFP 1 recover to the standby state. Specifically, the CPU 11 performscontrol such that power is supplied to the sensor unit 60 and thescanner unit 40.

In step S1410, the CPU 11 makes the scanner unit start reading adocument. In step S1411, the CPU 11 transmits image data of an imageread by the scanner unit 40 to the information processing apparatus 2.

In step S1403, the CPU 11 determines whether the received stateacquisition request is in accordance with the pullscan protocol. If thestate acquisition request is determined to not be in accordance with thepullscan protocol (NO in step S1403), the CPU 11 does not make thesensor unit 60 recover. In addition, the information indicating thestate of the scanner unit 40 is not updated. In step S1412, the CPU 11transmits the not-updated information indicating a temporary state ofthe scanner unit 40 to the transmission source of the state acquisitionrequest.

In step S1402, if the CPU 11 determines that the factor responsible forthe interrupt is not the state acquisition request transmitted from theinformation processing apparatus 2 (NO in step S1402), then in stepS1413, the CPU 11 makes the MFP 1 recover from the power saving state.If the operation unit 20 is operated by the user, if the facsimile unit50 receives a facsimile, or if the NIC 15 receives data from the LAN,then in step S1413, the MFP 1 recovers from the power saving state andenters the standby state.

An image reading apparatus according to an embodiment of the presentinvention recovers from the power saving state according to the stateacquisition request transmitted before the read request is transmitted.As a result, the image reading apparatus can respond to the stateacquisition request with the state of a document to be read.

Other Embodiments

Embodiments of the present invention can also be realized by a computerof a system or apparatus that reads out and executes computer executableinstructions recorded on a storage medium (e.g., non-transitorycomputer-readable storage medium) to perform the functions of one ormore of the above-described embodiment(s) of the present invention, andby a method performed by the computer of the system or apparatus by, forexample, reading out and executing the computer executable instructionsfrom the storage medium to perform the functions of one or more of theabove-described embodiment(s). The computer may comprise one or more ofa central processing unit (CPU), micro processing unit (MPU), or othercircuitry, and may include a network of separate computers or separatecomputer processors. The computer executable instructions may beprovided to the computer, for example, from a network or the storagemedium. The storage medium may include, for example, one or more of ahard disk, a random-access memory (RAM), a read only memory (ROM), astorage of distributed computing systems, an optical disk (such as acompact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™),a flash memory device, a memory card, and the like.

While the present invention has been described with reference toembodiments, it is to be understood that the invention is not limited tothe disclosed embodiments. It will of course be understood that thisinvention has been described above by way of example only, and thatmodifications of detail can be made within the scope of this invention.

1. An image reading apparatus which reads an image of a documentaccording to a read request transmitted from an external device, theimage reading apparatus comprising: a reader which reads an image of adocument; a document feeder which feeds a document to the reader; asensor which senses a document to be fed by the document feeder; anetwork interface which receives a predetermined request from theexternal device; and a controller which supplies power to the sensor ona basis that the network interface receives the predetermined requestwhile the image reading apparatus is in a low-power state in which powerto the sensor is stopped, and transmits a sensing result of the sensorto the external device as a response to the predetermined request. 2.The image reading apparatus according to claim 1, wherein power to thereader is stopped in the low-power state.
 3. The image reading apparatusaccording to claim 2, wherein the controller supplies power to thesensor without supplying power to the reader on the basis that thenetwork interface receives the predetermined request while the imagereading apparatus is in the low-power state.
 4. The image readingapparatus according to claim 1, wherein the read request and thepredetermined request are transmitted from a scan driver executed in theexternal device.
 5. The image reading apparatus according to claim 1,wherein the controller transmits the sensing result and at least one ofan execution state of the reader and error information of the reader asa response to the predetermined request.
 6. The image reading apparatusaccording to claim 1, wherein the predetermined request and the readrequest are each a request transmitted according to a predeterminedprotocol.
 7. The image reading apparatus according to claim 1, whereinthe network interface receives another predetermined request fromanother external device and the controller transmits a sensing result ofthe sensor to the other external device as a response to the otherpredetermined request.
 8. The image reading apparatus according to claim7, wherein the controller does not supply power to the sensor on a basisthat the network interface receives the other predetermined requestwhile the image reading apparatus is in the low-power state, andtransmits the sensing result of the sensor to the other external deviceas the response to the other predetermined request.
 9. The image readingapparatus according to claim 7, wherein the sensing result as theresponse to the other predetermined request is information stored inadvance before the image reading apparatus is shifted to the low-powerstate.
 10. The image reading apparatus according to claim 1, wherein thecontroller supplies power to the reader on a basis that the networkinterface receives the read request while the image reading apparatus isin a power saving state in which power to the reader is stopped.
 11. Theimage reading apparatus according to claim 1, wherein the controllerstops to supply power to the sensor after the controller transmits thesensing result.
 12. The image reading apparatus according to claim 11,wherein the controller supplies power to the sensor and the reader on abasis that the network interface receives the read request while theimage reading apparatus is in a power saving state in which power to thesensor and the reader is stopped.
 13. The image reading apparatusaccording to claim 12, wherein the reader reads an image of a documentin accordance with the read request.
 14. The image reading apparatusaccording to claim 1, wherein the read request includes a first readrequest that the reader reads a document placed on an automatic documentconveyance apparatus, or a second read request that the reader reads animage of a document placed on a transparent plate, and wherein thereader, if the first read request is received, reads a document placedon the automatic document conveyance apparatus, and if the second readrequest is received, reads a document placed on the transparent plate.15. The image reading apparatus according to claim 1, wherein thenetwork interface updates a pre-stored sensing result and transmits theupdated sensing result to the external device as the response to thepredetermined request.
 16. The image reading apparatus according toclaim 1, wherein the predetermined request is transmitted before theread request is transmitted.
 17. The image reading apparatus accordingto claim 1, further comprising a printer that forms an image on a sheet.18. A method for controlling an image reading apparatus including areader which reads an image of a document, a document feeder which feedsa document to the reader and a sensor which senses a document to be fedby the document feeder, the method comprising: shifting the imagereading apparatus to a low-power state in which power to the sensor isstopped; receiving a predetermined request from an external device;supplying power to the sensor based on receiving the predeterminedrequest while the image reading apparatus is in the low-power state; andtransmitting a sensing result of the sensor to the external device as aresponse to the predetermined request.
 19. The method according to claim18, wherein the supplying is supplying power to the sensor withoutsupplying power to the reader based on the reception of thepredetermined request.
 20. The method according to claim 18, furthercomprising: receiving another request from another external device; andtransmitting sensing result of the sensor to the other external deviceas a response to the other request; wherein the image reading apparatusdoes not supply power to the sensor based on receiving the otherpredetermined request while the image reading apparatus is in thelow-power state.